Path: utzoo!mnetor!uunet!husc6!cca!g-rh
From: g-rh@cca.CCA.COM (Richard Harter)
Newsgroups: comp.lang.c
Subject: Re: The D Programming Language
Message-ID: <25203@cca.CCA.COM>
Date: 3 Mar 88 05:34:28 GMT
References: <11702@brl-adm.ARPA> <243@eagle_snax.UUCP> <2245@geac.UUCP> <2718@mmintl.UUCP> <2327@umd5.umd.edu> <2731@mmintl.UUCP> <24935@cca.CCA.COM> <2736@mmintl.UUCP>
Reply-To: g-rh@CCA.CCA.COM.UUCP (Richard Harter)
Organization: Computer Corp. of America, Cambridge, MA
Lines: 43
Summary: Resolving dangling else's

In article <2736@mmintl.UUCP> franka@mmintl.UUCP (Frank Adams) writes:
>In article <24935@cca.CCA.COM> g-rh@CCA.CCA.COM.UUCP (Richard Harter) writes:
||	if (boolean expression)
||		....
||		end
||	else
||		....
||		end
|
|Note that this does *not* solve the dangling else problem.  That being the
|case, I see no reason to prefer it to the current syntax.

	I wasn't suggesting it as a resolution of the dangling else problem,
because, as you note, it isn't whether or not one has labels.  It struck me
as an idea that might have some value -- and it might if the compiler pro-
duced a listing that labelled each line with the block that was part of.
I am now persuaded that the idea has no particular merit.

	If one is really concerned about the dangling else problem there
is a very simple solution -- use different keywords for two sided if's and
one sided if's.  For example, the presence of a 'then' keyword guarantees
an 'else' and its absence guarantees the lack of an 'else'.  E.g. 

if (e1) then
   if (e2) A;
   else B;  <---- this pairs with the first if

if (e1)
   if (e2) then A;
   else B;  <---- this pairs with the second if

if (e1)
   if (e2) A;
   else B;  <---- this is a syntax error

	Another cure is to always require that an 'else' statement be
present, even it if it is null.  Personally, I am inclined to feel that
all of the cures (including endif) are worse than the disease.
-- 

In the fields of Hell where the grass grows high
Are the graves of dreams allowed to die.
	Richard Harter, SMDS  Inc.